The intake manifold of a running internal combustion engine generally operates under negative pressure by which an air-fuel mixture is drawn through the intake manifold and into the cylinders. Because of the pressure differential between the intake manifold and ambient air, it is possible for liquid water to enter and accumulate in the intake manifold. An example of such a situation arises where the vehicle is passed through deep standing water. Another example of such a situation arises during times of excessive rain.
If even a small amount of accumulated liquid water enters one or more of the cylinders, an engine misfire can result. The entry of liquid water into the engine may also cause the failure of one or more sensors, such as the throttle position sensor, as some sensors are sensitive to the presence of water. If a larger amount of water enters a cylinder, engine damage in the form of a bent or broken connecting rod may result. This is the case because liquid water is not compressible, and when the piston moves toward the top of the combustion chamber during the compression stroke, even a small amount of liquid water can provide sufficient non-compressive mass to resist the free movement of the piston.
In an effort to restrict the inflow of liquid water from the intake manifold into the cylinders, water containment features have been introduced into the lower portion of the manifold. However, known containment features still allow liquid water to enter the cylinders, thus causing misfiring, sensor failure, and engine damage as noted above.
Accordingly, as in so many areas of vehicle technology there is room for improvement related to methods and systems for restricting the flow of liquid water from the intake manifold into the cylinders of an internal combustion engine.